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Mohs Micrographic Surgery: A Historical Perspective
Dermanities August 24, 2003; 1(3)
Anatoli Freiman, MD and Patricia T Ting, BSc
Division of Dermatology, McGill University Health Center
and University of Calgary, Canada
In the early 1930s, as a medical student, Fredrick E. Mohs pioneered the idea of microscopically-controlled removal of cutaneous tumors. With its ability to systematically examine 100% of lesion margins, Mohs Micrographic Surgery (MMS) allows for maximal sparing of normal tissues and provides excellent cosmetic results. Whereas today it is considered one of the greatest contributions to the field of dermatologic surgery, the widespread acceptance of the technique took over 50 years. We review the key historical events in the development of MMS.
In the early 1930's, as a young medical student at the University of Wisconsin, Frederick E. Mohs worked as an assistant in a cancer research laboratory, investigating the effect of various irritants on implanted cancers in rats. Mohs observed that injections of 20% zinc chloride effectively and accurately penetrated the tissues without systemic toxicity. The chemical was also safe to handle, as it did not diffuse into the keratin layer of the skin, unless a keratolytic, such as dichloroacetic acid, was previously applied. Most importantly, this zinc preparation maintained the histologic architecture of these tissues 1,2. Mohs subsequently proposed the concept of chemical fixation followed by surgical excision of tumors with microscopic examination of tumor margins. And thus, the concept of micrographic chemosurgery was born.
In 1936, after formal training as a general surgeon, Dr. Mohs began treating patients with cutaneous malignancies in the dermatology clinic at the Wisconsin General Hospital. An elderly pharmacist at the drug store supplied him with the ingredients required for the topical fixative paste containing stibinite (an antimony ore, which served as a granular matrix) and sanguinaria canadenis (a binder for the saturated solution of zinc chloride). Mohs would start by applying the in-situ fixative to cutaneous neoplasms and allowed fixation to occur over 12 to 24 hours3. The fixated tissue was surgically excised in a saucer-like configuration, and frozen horizontal sections were microscopically examined. Subsequently, he refined his technique by color-coding the specimen edges with red (merbromin), blue (laundry bluing) and black (India ink) dyes. This procedure provided a precise reference map of the tumor to be drawn and juxtaposed on to the corresponding sites in the surgical wound bed. If microscopic examination revealed residual malignant tissue, re-application of the fixative for 24 hours and further serial removal of affected tissues would ensue 3. The process of fixation, surgical excision and microscopic examination was repeated until the margins were clear and the entire tumor was removed. The wound was then allowed to heal by secondary intention as the fixative sloughed over the course of 7 to 10 days 3-5.
Initially, Mohs' pioneering surgical concept for the treatment of cutaneous malignancies was not well accepted by the medical community. Physicians were concerned that although the fixation process allowed for bloodless excision of tissue, patients reported extreme pain secondary to the caustic effects of zinc chloride, which induced edema and tissue necrosis. In addition, local tissue inflammation from the fixation often made it difficult to interpret tumor histopathology. The surgical process was also extremely labor intensive, and the time required to microscopically examine the tumor and repeat the entire process for incompletely excised margins delayed surgical reconstruction and closure of the wound bed, as well as increased rates of infection4. Furthermore, the medical community believed that the inflammatory reaction and cutting through tumors could promote local seeding of tumor cells and facilitate metastatic spread. Therefore, surgeons at the time preferred to use conventional wide surgical margins 5.
While the general medical community did not support Mohs' technique, several surgeons at the Wisconsin General Hospital were interested 2. In 1940, Mohs' clinic was transferred to the department of surgery where a supportive chief, Dr. Erwin Schmidt, prepared a foreward for the first clinical article about Mohs' technique published in the Archives of Surgery6. After Mohs made a presentation at the annual meeting of the American Academy of Dermatology in 1946, his technique caught the attention and interest of dermatologists of who recognized the useful applications of the procedure5. Soon after, many dermatologists came to observe and train with Dr. Fredrick Mohs in his clinic at the University of Wisconsin.
Some of those trainees made significant contributions to the development and improvement of the procedure. In 1951, Dr. Ray Allington suggested that dichloroacetic acid could be used for hemostasis after the debulking procedure. A monumental change in Mohs fixed tissue technique serendipitously occurred in 1953 during the filming of an instructional documentary demonstrating Dr. Allington's suggestion for the procedure on a multistage removal of an eyelid basal cell carcinoma 5. Due to the time constraints of the filming session, Mohs injected the residual tumor area with local anesthetic and omitted the second round of the zinc chloride fixation; it was soon realized that the resolution of tumor margins was not significantly impeded without fixation. This became known as the fresh-tissue technique, which was also illustrated in Mohs' chapter in the first edition of Epstein's Skin Surgery in 19566. With this procedural modification, patients experienced significantly less pain and morbidity. Because of the absence of tissue inflammation and sloughing, which were previously observed secondary to zinc chloride application, more tissue could be conserved and reconstruction of the wound bed could now take place on the same day as the excision4.
Several years later, the procedure gained wide acceptance, eventually leading to the establishment of American College of Chemotherapy in 1968. At the annual meeting in 1970, Dr. Theodore Tromovitch, who had been using the fresh tissue technique since the 1960s, presented a case series of 75 patients treated for cutaneous carcinomas and reported equally high cure rates with this new technique7, which also proved that the real reason for the success of the fresh-tissue Mohs surgery was not the chemical fixation of the tissue, but the microscopic control. In 1986, the society was renamed the American College of Mohs Micrographic Surgery and Cutaneous Oncology (ACMMSCO) and minimum one year fellowships in Mohs Micrographic Surgery were officially regulated via this organization5. The fellowship requires specialized training in a composite of skills including dermatopathology and reconstructive surgery.
"Winning general acceptance takes much patience," once said Dr. Fredrick Mohs2. The development and widespread acceptance of Mohs micrographic surgery has taken over 50 years2. Although the original concept of micrographic surgery began in the early 1930s, 12 years elapsed before the development of the original fresh tissue technique (1936 to 1948), and its use for cutaneous carcinomas did not begin until 17 years later (1953 to 1970). With its ability to systematically examine 100% of tumor margins, Mohs Micrographic Surgery allows for maximal sparing of normal tissues and provides excellent cosmetic results. Today, it is considered one of the greatest contributions to the field of dermatologic surgery8.
1 Mohs FE, Guyer MF. Pre-excisional fixation of tissues in the treatment of cancer in rats. Cancer Res 1941; 49.
2 Mohs FE. Mohs micrographic surgery. A historical perspective. Dermatol Clin 1989; 7: 609-11.
3 Shriner DL, McCoy DK, Goldberg DJ, Wagner RF, Jr. Mohs micrographic surgery. J Am Acad Dermatol 1998; 39: 79-97.
4 Kovach R, Welton WA, Wetmore SJ. Mohs micrographic surgery. W V Med J 1990; 86: 551-5.
5 Brodland DG, Amonette R, Hanke CW, Robins P. The history and evolution of Mohs micrographic surgery. Dermatol Surg 2000; 26: 303-7.
6 Mohs FE. Chemosurgery. A microscopically controlled method of cancer excision. Arch Surg 1941; 42: 279-95.
7 Tromovitch TA, Stegman SJ. Microscopic-controlled excision of cutaneous tumors: chemosurgery, fresh tissue technique. Cancer 1978; 41: 653-8.
8 Hanke CW, Francis LA. Growth in skin surgery. Clin Dermatol 1992; 10: 257-63.
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The authors have no conflict of interest to disclose.
This work has not been supported by any funding sources.
It has been presented in part at McGill Dermatology Rounds, March 2003.